Binding of the cationic dye, Janus green B, as a measure of the specific surface area of crystalline silica in aqueous suspension.
Daniel LN; Mao Y; Vallyathan V; Saffiotti U
Toxicol Appl Pharmacol 1993 Nov; 123(1):62-67
The development of a new binding assay, with a simple and rapid method to obtain surface area measurements which would be applicable to small silica (14808607) samples in an aqueous environment was studied. Reproducible duplicate measurements were obtained on a large number of 2 milligram (mg) samples run concurrently using the Janus-green-B adsorption method. The Brunauer-Emmett-Teller (BET) method necessitated sample sizes in excess of 100mg and more specialized instrumentation. The lowest specific surface areas were found for Min-U-Sil-5 and F600 among four standard alpha-quartz samples tested. Much higher surface areas were observed with DQ-12 and Chinese standard alpha-quartz samples. Cristobalite (14464461) and tridymite (15468323), two synthetic silica preparations, had intermediate surface areas. The authors conclude that binding by Janus-green-B is consistent with a surface charge mechanism and provides a new technique useful in assessing surface characteristics of samples of crystalline silica. The fact that the ratio of aqueous surface charge to surface area is constant for different crystalline silica preparations is suggested by the linear relationship to surface area. The authors note that the relative activities of these silica preparations is important in understanding their roles in the mechanisms of both silicosis and silica induced lung cancer.
NIOSH-Author; Silica-dusts; Dust-exposure; Airborne-dusts; Miners; Respiratory-system-disorders; Mineral-dusts; Carcinogenesis; Airborne-particles
14808-60-7; 14464-46-1; 15468-32-3
Toxicology and Applied Pharmacology